Radiographic sheet



Feb. 20, 1951 c. E. BOUCHER 2,542,304

RADIOGRAPHIC sHEET Filed Dec. 29, 1950 Ramon awe /Z h/e/a Coaf/ny h L- scnsifizm /aye/' m BM WW Fla. 2

Removab/e sh/e/d coaf/ng Sens/fixed la yer Backing menvber Sens/fired layer Remara/e Shield (cuff/77 Parau: Z2 shield layer 2 'sensifr'zed layer 1-Backing member Cormack f. Boucher INVENTOR.

B Y KIM W (M Patented Feb. 20, 1951 UNITED STATES PATENT OFFICE 2,542,304 RAnrocRAPHio SHEET Cormack E. Boucher, Seattle, Wash: msiiiitandiineenster 29, 19st", sense No. 203,272

'lillainis;

' The present invention relates to radiographic sheets for use in making radiographs by means of penetrative rays.

This application is a continuation in part 'of my previous application Serial No. 766,206, filed August 5, 1947, now abandoned.

Radiographic sheets, either film or paper, now in common usage are sensitive to visible light rays as well as to pen'etrative rays s'othat it is necessary to mcwse the sheets within separate opaque envelopes or holder'sto protect the sheets against xptsure due tov'isible lightrays. The sensitized sheets of the prior art are usually packaged in light'prooi boxes, 'and the individual sheets arrequired to be loaded into'the envelopes or holders by the user in a dark room. lifter exposure, the sheetsmust'be removed from the holder within a dark room and then put through a" development process which must aiso be carried on within the dark room.

It is an object of the present invention to provide a new and improved radiog'raphic sheet which may be handled in daylight and which does not require the useoi light proof envelopes. Another object is to provide a'unitary sensiti zed' sheet particularly suited for radiography and which is sensitive to only a predetermined band of radiations. U

Another object is to provide" a unitary composite sensitized sheet particularly suited for radiography which is selectively sensitive to 'only a" predetermined band of radiations in the in visible spectrum and which after exposure may bepr'oce's'sed under ordinary 'lightconditions.

A further object of the invention is'to provide anew and improved unitary radiographic sheet including a sensitized layer, the sheet beingfurther provided with an additional layer covering the" sensitized layer and shielding the same against exposure by a certain band of rays but permitting exposure thereof by another predetermin'ed band of rays. H

A still further object of the invention is to provide a new and improved unitary sensitized sheet particularly suited for radiography, the sheet including a sensitized layer which is sensitive to a wide band of radiations and a' protective layer covering the sensitized layer wherebythe "sensitized layer is subject to exposure by only'a selective band of radiations. n

1 In accordance with one form of the present invention, a radiographic sheet is provided coinprising a backing member made of opaque ma t? iaQl or having an opaque coating, the backing member being provided with a sensitized layer on-b'ne side, the sensitized layer, in turn, being covered with a'reinova-ble opaque layer such as, for example, a soluble coating, applied directly over the sensitized layer, the sensitized layer being adapted to be exposed by penetrative rays, and the removable opaque layer being adapted to be'removed or'dissolved during the processing of the sensitized layer, but after the sensitized layer has been rendered insensitive to visible light.

For a consideration-of what is believed novel and inventive, attention-is directed to the follow.- ing description taken in connection with the accompanying drawing while the features of novelty will be pointed out with greater-particularity in the appended claims.

In the drawing, Fig. 1 is an enlarged crosssectional view of a radiographic sheet in accord"- ance with one modification of the present invention; and Fig. 2 is an enlarged cross-sectional view illustrating a second modification of the invention; and Fig. 3 is an enlarged cross sectional view illustrating a third modification of the invention. 7 I

'ljhe radiographic sheet of the present inven-. tion is designed primarily for use in making radiographs by means of penetrative rays. By

the'fterm penetrative rays is meant Xeays,

gamma rays, or any other similar radiations of such short wave lengththat they may penetrate through relatively dense objects being radiographed and produce an image eiTect upona sensitized layer positioned behind the object.

Referring to the drawings, the unitary radio'- graphic sheet shown in Fig. 1 comprises a backing member H) which is coated on one side with a sensitized layer H. The layer II may be of any form well known in the art and in use on radiographic films and papers. Such emulsion layers are ordinarily sensitive to a wide band of radiations extending from the infrared through out the visible spectrum and the invisible spectrum therebelow. The backing member 50 may be either film or paper but for the moment it will be considered as being paper and in which event it should be of such material or so coated as to shield the reverse side of the sensitized layer II from all rays other than those which are to be used in the exposure of the sensitized layer l I. The sensitized layer H is covered with a further removable layer I2 applied directly thereto whereby the upper surface of the layer I I opposite the backing member i0 is also shielded against radiations other than those to be used in causing exposure'of the sensitized layer.

merely opaque. The backing member it may be rendered opaque in any suitable manner.

The layer l2 superimposed over the sensitized layer It may be formed of any suitable material or composition. For example, it may consist of an opaque soluble gelatinous or adhesive substance which is removable by washing or by stripping during the processing of the sheet following exposure thereof, but after the sensitized layer has been rendered insensitive to visible light. The layer l2 should be formed of a liquid permeable substance whereby the developer solution may pass readily therethrough for effecting the development of the sensitized layer l l but without causing the removal of the layer l2. The solvent for the layer !2 may be included in the fixing solution whereby it will be removed only after all danger of fogging of the sensitized layer H by visible light is past. It will be obvibus that it is not essential for the coating 12 to be entirely removed but only that its initial opaque character be changed to one of trans-par ency whereby the image developed within the sensitized layer H will be visible therethrough.

It is to be understood that the present invention is not to be limited to any particular type of opaque coatings since suitable coatings may readily be compounded by anyone skilled in the art. For example, one suitable coating composition was prepared of the following ingredients:

Parts Aqueous animal gelatine '57 Glycerin I 27 Carbon black 10.5

Water 116 The gelatine, orrplasti ized animal glue, was first melted with the glycerin, on a water bath and one-fourth to one-half the water added when 'the melt started. When the ingredients were thoroughly blended the carbon black, for example, oil-free lampblack, was added with continued stirring, until a smooth lump-free mixture was obtained. Finally the remainder of the water was added. A few tenths part of a wetting agent may be added for improved smoothness and spreading properties.

An X-ray film coated in a dark room on all sides with this composition was exposed by X-rays under daylight conditions and subsequently processed also under ordinary room illumination. The developer and fixing solutions readily permeated the opaque coating and fully processed Ounces Aqueous colloidal graphite (30%) M 32 Water 32 Polyvinyl alcohol 8 glycerin 1 The alcohol was moistened with one pint of water and heated in a pressure cooker to facilitate solution. 'l'he graphite suspension and water were then stirred in and the mixture then heated on a water bath until a smooth homogenous product was obtained. 'An X-ray film coated with this mixture was exposed in daylight and processed under ordinary room illumination as in the former case. The bond between the coating and the film was softened by the processing solution so that it was easily stripped from the film and the same satisfactory results were noted as above.

A satisfactory opaque coating composition was also prepared using an aqueous mixture of corn starch and oil-free lampblack together with a quantity of fine uniform cellulose fibers. A film coated with this mixture was exposed by X-rays and processed, both under daylight conditions of illumination. The coating softened suificiently during the processing procedure to permit it to be stripped free of the film, and the sensitized layer was found to be fully developed and fixed, the image sharp and clear with no evidence of fog ing. v 1

Numerous other opaque coatings were compounded and tried with satisfactory results and still others will readily occur to one skilled inthe art.

In the case of radiographic film such as X -ray film the backing member consists of a transparent sheet and which is coated on both sides with a sensitized emulsion layer. In Fig. 2 such a backing member 14 is shown which is coated on its opposite sides with sensitized emulsion layers It and [6. In accordance with the present invention removable shielding coatings I! and H] are applied over each of the coatings l5 and I6 and which are similar to the coating i2 as previously described in connection with Fig. 1.

In modification of the invention illustrated in Fig. 3, the backing member 2| is coated with a sensitized layer 20 and which is in turn covered with a sheet 22 of an absorptive or porous material, such as soft paper. The sheet 22 is opaque so as to shield the sensitized layer 20 against exposure byradiations other than those which are to be used in exposing the layer 20. The porous sheet 22 may be 'adhesively secured onto the surface of the sensitized layer 20 throughout the full extent thereof or at least around the peripheral edges of the sheet. The

porous sheet 22 is readily permeable to liquid solutions whereby the entire sheet may be immersed in developer solution for effecting development of the sensitized layer ll. After development, the sheet may be transferred to a vessel containing fixing solution and which may include a solvent for the adhesive film securing the sheet 22 to the backing member 2|. How;- ever, the sheet 22 may be manually removable as by stripping from the backing member. An absorptive porous sheet such as 22 may be substituted for either of the coatings l2, or H and [8, previously described.

The porous sheet 22 may be secured in place by aqueous animal or fish glue over the entire surfaces of the film so as to exclude any air bubbles therebetween which might interfere with uniform development of the sensitized layer. While the developing and fixing solutions may soften the glue, it retains'a sufficient amount of adhesion to hold the opaque layer in place for the period required to render the sensitized layer insensitive to visible light, after which the opaque layer may be readily stripped from the film.

It will be obvious that the shielding coatings described above should extend around the edges of the sheets in order that the sensitized layer will not be fogged due to exposure by rays penetrating edgewise of the sheet.

The radiographic sheet of the present invention is economical to use since it may be handled in visible light and does not require the usual light-proof envelopes or holders. The time required for loading and unloading of ordinary film or paper into such receivers is eliminated as well as the expense of the light proof receivers themselves. The necessity for a dark room usually required for loading and unloading receivers with ordinary film is also eliminated.

Moreover, the need for a dark room for processing the film following exposure thereof is also dispensed with.

What I claim is:

1. A radiographic sheet comprising an opaque backing member, a sensitized layer on one surface of said backing member sensitive to penetrative radiations, and an opaque porous sheet adhesively secured onto the upper surface of said sensitized layer and a layer of soluble adhesive securing said porous sheet onto the upper surface of said sensitized layer.

2. A radiographic sheet comprising a backing member, a sensitized layer on one surface of said member sensitive to penetrative radiations, a second layer permeable to processing solutions covering said sensitized layer, said second layer being indestructible by normal processing solutions for said sensitized layer, said second layer being opaque and removable after said sensitized layer is processed to a condition insensitive to visible light.

3. A radiographic sheet comprising a backing member, a sensitized layer on one surface of said backing member sensitive to penetrative radiations, a second layer permeable to processing solutions for said sensitized layer covering said sensitized layer, said second layer being opaque whereby said radiographic sheet may be processed in visible light, the opacity of said second layer in place upon said backing member being unaffected by said processing solutions at least until after said sensitized layer has been rendered insensitive to visible light, said second layer being removable following processing of said sensitized layer to a condition of insensitiveness to visible light.

4. A unitary sensitized sheet particularly suited for radiography, said sheet including a sensitized layer sensitive to a relatively wide band of radiations, said sheet including additional protective means opaque to radiations other than within a selective portion of said wide band for protecting said layer from exposureby radiations outside of said selective portion of said wide band, said means being readily permeable to processing media for said sensitized layer, the protective nature of said means being unaffected by said processing media prior to transformation of said sensitized layer to an insensitive condition.

5. A unitary sensitized sheet particularly suited for radiography, said sheet including a backing member having a sensitized coating thereupon sensitive to a relatively wide band of radiations in both the visible and invisible spectrums, said sheet including protective shielding means for protecting said coating from exposure by radiations other than those within a portion of the invisible spectrum, said shielding means being readily permeable to processing media for said sensitized coating while remaining in place upon said sheet, said shielding means being substantially unaffected by subjection to said processing media at least prior to transformation of said sensitized coating by said media to an insensitive condition.

6. A radiographic sheet comprising a backing member, a sensitized layer on one surface of said member normally sensitive to visible light and to penetrative radiations, a second layer permeable to processing solutions for said sensitized. layer covering said sensitized layer, said second layer being opaque and indestructible in place by said processing solutions at least until after said sensitized layer is transformed by processing solutions to a condition insensitive to visible light, said second layer being separable from said sheet following processing of said sensitized layer.

7. A radiographic sheet comprising an opaque backing member, a sensitized layer on one sur face of said backing member sensitive to penetrative radiations, and an opaque porous paper sheet covering said sensitized layer, said paper sheet being readily permeable to processing solutions for said sensitized layer.

CORMACK E. BOUCHER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,536,341 I-Iodgson May 5, 1925 1,911,955 Heinecke et a1 May 30, 1933 2,021,190 Malkasian r- Nov. 19', 1935 FOREIGN PATENTS Number Country Date 11 L933 Great Britain Apr. 25, 1918 

1. A RADIOGRAPHIC SHEET COMPRISING AN OPAQUE BACKING MEMBER, A SENSITIZED LAYER ON ONE SURFACE OF SAID BACKING MEMBER SENSITIVE TO PENETRACTIVE RADIATIONS, AND AN OPAQUE POROUS SHEET ADHESIVELY SECURED ONTO THE UPPER SURFACE OF 